One of the –in my opinion- most impressive features I have seen in mathematics software is the recent fusion of the Freudenthal Institutes (FI) DME (Digital Mathematical Environment), good content and the ability to plug in components like Geogebra. Of course, it also is software that I know well, because my thesis (www.algebrametinzicht.nl) also used the DME.
For the DPICT project of the FI several lesson series were also translated to English. One of them concerned Geometry. Articles and papers of the project will appear, but I think the material warrants an impression in screenshots.
Accessing the Geometry module:
Geometric construction on the right side can be checked. There are open textboxes (which can’t be checked on correct or incorrect, but can be accessed by the teacher). Note that the [c] task, a drop and drag task, was answered incorrectly.